We were there in Feb with another (larger, younger) family in a GV. We went grocery shopping and needed BULK because of the kids and length of stay.
On Katella, make a right. Maybe 1.5 to 2 miles, on the left, in a strip center, there a Food4Less (I think that was the name).
It was a HUGE plain vanilla store with lots of good prices. At least my wife and her friend thought so, and bought a ton of stuff. I was just along to drive, push the cart, and load the bags. Typical husbandy duties.